3.4.2 Electromotive force and internal resistance Quiz: Pearson Edexcel Physics, Unit 3

The 20 questions

1. What quantity represents total energy transferred per unit charge by a source into electrical energy?

   • Internal resistance
   • Electrical power
   • Terminal p.d.
   • Electromotive force

2. What causes energy dissipation inside a power source when current flows through it?

   • Supply e.m.f.
   • External resistance
   • Internal resistance
   • Terminal p.d.

3. Compared to e.m.f., terminal p.d. measures energy transferred per unit charge where?

   • Across internal resistance
   • Inside the cell
   • Through total loop
   • In external circuit

4. Which equation gives the terminal p.d. V of a cell with e.m.f. E and internal resistance r when it supplies a current I?

   • V = Ir - E
   • V = E + Ir
   • V = E/r - I
   • V = E - Ir

5. On a graph of terminal p.d. against current, what does the y-intercept represent?

   • Electromotive force
   • Internal resistance
   • Load resistance
   • Lost volts

6. In a cell circuit, what term describes the potential difference across the internal resistance?

   • Terminal p.d.
   • Electromotive force
   • Lost volts
   • Supply voltage

7. What is the current when a cell of e.m.f. E and internal resistance r is short-circuited?

   • E r
   • E/(2r)
   • Zero
   • E/r

8. A cell of e.m.f. 1.5 V and internal resistance 0.50 ohm supplies a current of 0.40 A. What is its terminal p.d.?

   • 1.3 V
   • 1.5 V
   • 0.20 V
   • 1.7 V

9. A cell of e.m.f. 2.0 V and internal resistance 0.50 ohm is connected to a 2.5 ohm resistor. What current flows?

   • 0.40 A
   • 0.80 A
   • 0.67 A
   • 4.0 A

10. Three identical cells, each of e.m.f. 1.5 V and internal resistance 0.20 ohm, are connected in series to a 4.0 ohm resistor. What current flows?

    • 1.1 A
    • 0.98 A
    • 1.5 A
    • 0.33 A

11. Two identical cells, each of e.m.f. 1.5 V and internal resistance 1.0 ohm, are connected in parallel. What are the e.m.f. and internal resistance of the combination?

    • E = 1.5 V and r = 2.0 ohm
    • E = 3.0 V and r = 2.0 ohm
    • E = 1.5 V and r = 0.5 ohm
    • E = 3.0 V and r = 0.5 ohm

12. A line of terminal p.d. against current has V-intercept 1.6 V and passes through the point (0.40 A, 0.80 V). What is the internal resistance?

    • 4.0 ohm
    • 1.6 ohm
    • 0.50 ohm
    • 2.0 ohm

13. A cell has e.m.f. 6.0 V and internal resistance 0.50 ohm, and supplies a current of 4.0 A. What is its terminal p.d.?

    • 6.0 V
    • 4.0 V
    • 2.0 V
    • 8.0 V

14. A cell of e.m.f. 2.0 V and internal resistance 0.50 ohm is connected to an external resistor of 1.5 ohm. What power is dissipated in the external resistor?

    • 0.50 W
    • 2.0 W
    • 1.0 W
    • 1.5 W

15. A cell of e.m.f. 1.5 V transfers a total charge of 120 C round a circuit. How much energy is transferred by the cell?

    • 180 J
    • 120 J
    • 80 J
    • 1.5 J

16. A cell of e.m.f. 3.0 V and internal resistance 1.0 ohm supplies two 4.0 ohm resistors connected in parallel. What is the terminal p.d.?

    • 1.0 V
    • 2.5 V
    • 2.0 V
    • 3.0 V

17. A cell has e.m.f. 1.5 V and delivers a current of 1.0 A with terminal p.d. 1.0 V. What is the efficiency of the cell, as terminal p.d. divided by e.m.f.?

    • 50%
    • 100%
    • 33%
    • 67%

18. Why does terminal p.d. drop as current drawn from a cell increases?

    • External resistance drops
    • Lost volts increase
    • E.m.f. decreases
    • Internal resistance falls

19. A cell of e.m.f. 12 V and internal resistance 2.0 ohm drives a circuit whose total external resistance is 7.0 ohm. What current flows?

    • 2.0 A
    • 0.86 A
    • 1.3 A
    • 1.7 A

20. Why does a high-resistance voltmeter placed across an unloaded cell measure its e.m.f.?

    • Negligible current flows
    • Terminal p.d. drops
    • Internal resistance drops
    • Current becomes infinite

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